This invention relates to an apparatus for the containment of carbonated beverages, and the like, and more particularly to a variable volume container for such beverages intended to maintain high levels of carbonation in a partially filled container. It is well known that effervescent beverages, such as flavored and unflavored carbonated soda water, beer, sparkling wines, liquid laxatives, etc., tend to lose their carbonation once the container has been opened. The higher is the liquid temperature, the more rapid will be the escape of gas from the liquid. Also, agitation of the liquid tends to accelerate the outflow of gas. After a major portion of gas has escaped from the stored liquid, the beverage has lost its bubbling, fizzy characteristic and is flat. Thus, a most desirable quality of the beverage has been lost.
For this reason, when, for example, a container of soda water has been opened and partially dispensed, it is preferable in attempting to maintain the bubbling characteristic of the remaining portion, to reseal the container opening. For this purpose, the well known screw-type caps with resilient sealing surfaces are provided with many soda bottles. After a portion of soda is poured from the bottle, the cap is replaced and the resealed bottle is generally placed in a refrigerator until the next use. For bottles without screw-type caps there are many well known inexpensive devices which are available for purchase, which serve to reseal, with varying degrees of success, an opened bottle.
Unfortunately, although the bottle has been resealed to prevent spillage or pouring, a quantity of carbonating gas still escapes from the liquid and creates a partial pressure in the space above the liquid. The sealed space above the liquid contains ambient air, which is present when the cap is tightened, and in time, the carbonating gas from the liquid. Other gases may also be present which outgas from the liquid, for example, water vapor. The total pressure within the sealed space above the liquid is the summation of the partial pressures of each gas which is present and is generally higher than room ambient pressure. The pressure of carbonating gas in the space of the liquid is directly related to the liquid temperature. The weight quantity of carbonating gas which escapes the stored liquid to be contained above the liquid is thus dependent at least on the liquid temperature, the carbonating gas temperature and pressure in the space above the liquid, and on the volume of space above the liquid in the container.
When the bottle cap is removed to pour yet another portion of soda water (for example in the following description), the gas above the liquid, including the carbonating gas, is partially or fully vented off to the ambient environment usually before pouring is possible. The effervescent content of the decanted liquid is reduced as compared to the quantity of "fizz" in the earlier poured portion from that bottle. When the container holds a greater volumetric portion of liquid as compared to the volume of gas, that is, when the bottle is more full of liquid than empty, the loss of gas from the liquid during storage between uses is relatively low. But, when the liquid volume remaining in the container is small in amount relative to the volume of the container, that is, when the bottle is nearly empty, the loss of carbonating gas is greater.
Thus, when a container is poured from, and resealed for several use cycles, the amount of gas remaining in each unit volume of liquid for each successive use cycle is less, and the gas loss from the liquid each time the container is resealed is relatively greater. The last drink of carbonated beverage from a large container after several pourings and resealing is frequently entirely flat or has no effervescence shortly after pouring.
Also, the loss problem is aggravated by the trend toward larger and larger bottles of carbonated soda water, with two quart and two liter sizes being quite common and approximate gallon sizes becoming more common. The larger bottles will likely have more pourings with intermittent resealings before they are empty, and in the process offer a greater volume for gas collection over the liquid. Thus, the liklihood of pouring a flat beverage from a larger bottle is increased.
What is needed is a method and apparatus for storing carbonated beverages in the original container without substantial loss in the effervescing qualities of the remaining liquid after a portion of portions of the original carbonated liquid content have been poured out. Also, it is desirable that the apparatus be simple and economical in construction and be reusable or recyclable in whole or in part. Further, the apparatus should be simple and safe to operate.